Duration of the inhibitory activity on histamine‐induced skin weals of sedative and non‐sedative antihistamines

The inhibitory effect of orally administered dexchlorfeniramine (4 mg/day), cyproheptadine (8 mg/day), astemizole (20 mg/day), loratadine (40 mg/day) and terfenadine (120 mg/day) on the size of histamine‐induced weals was tested by skin prick test with histamine in an open study including 23 healthy individuals. The antihistamines were administered for 2 days in the nationally recommended therapeutic doses. For all drugs the maximal weal suppression with the dosage chosen was recorded the day after the last dosage, being 29% (for dexchlorfeniramine), 72% (for cyproheptadine), 50% (for astemizole), 62% (for loratadine), and 56% (for terfenadine) of the baseline value. For the drugs in the same order the duration of the inhibitory effect of the drugs after the last dose administered was between 3–4, 7–11, 17–28, 4–7, and 4–7 days, respectively.